Refining hydrocarbon oil



Patented Apr. 14, 1936 UNITED sTAras PATENT OFFICE actress REFININGHYDROCARBQN 01L Robert E. Manley and Howard H. .Grois, Beacon,

N. Y., assignors to The Texas New" York, N. Y., a corporation ofDelaware No Drawing. Application December 9, 1932 Serial No. 646,485

2 Claims. (Cl. 196-13) This invention relates to refining hydrocarbonoil, and more particularly to refining mineral oil by solventextraction.

The invention contemplates the treatment and 5 refining of mineral oilwith mixed solvents containing furfural; by the use of certain solventmixtures containing furfural the mineral oil may be separated by theextraction method to produce oil fractions having desiredcharacteristics and substantially free from undesired components.

A solvent liquid suitable for mixing with the furfural, in accordancewith our invention, comprises a solvent selected from the esters ofcyclic hydrocarbons such, for example, as phenyl acetate or furfurylacetate.

We have found that in treating and purifying mineral oil by extractionwith furfural, the furfural may be used more effectively when mixed witha solvent liquid of the type mentioned above, which liquid, when usedbyitself, may have quite dissimilar or divergent. selective solvent actionupon the oil undergoing treatment.

The furfural and solvent liquid of dissimilar selective action may bemixed in any desired pro portion to produce a solvent liquid mixturehaving any desired selective action upon the particular oil undergoingtreatment. In-this way, it is possible to obtain from a given mineraloil stock, fractions of differing characteristics.

The modifying solvent liquid may be completely or only partiallymiscible with the furfural provided that where it is not completelymiscible with furfural, it is miscible with the oil underliquids and oilforms a two-layer system upon standing. One layer will compriseraflinate or some of which are of a moreparaflimc nature while othersare of a more naphthenic nature.

The former are characterized by their: light specific gravity and highviscosity index; while the latter are characterized by having a heavygrav- 5 ity and low viscosity index. Oils of high viscosity index, inother words, having a flat temperature viscosity relationship possesssuperior lubricating value for some purposes, as, for example, in

the lubrication of internal combustion engines. 10

Lubricating fractions as obtained from crude petroleum usually alsocontain objectionable constituents in the form of aromatic andunsaturated compounds as well as sulphur-bearing bodies. The removal ofthese constituents is desirable in 15 .order to produce products of lowsulphur content and free. from readily oxidizable bodies which tend,duringuse, to form sludge. Thus; in the manufacture of lubricating oils,we have found that mixtures of furfural with solvent liquids se- 20lected from the esters of the cyclic hydrocarbons are effective inextracting these objectionable bodies as Well as those constituentshaving a low viscosity index and thus produce lubricating oil productscharacterized by having a high degree 25 of stability and a highviscosity index.

Moreover, it is possible, by varying the proportion of ester tofurfural, to either increase or de crease the extent of extraction as,for example going treatment whereby. the mixture of solvent that portionof the oil insoluble in the furfural,

while the other will comprise the extract portion which is soluble inthe furfural. Both layers 40 may contain substantial amounts of themodifying solvent liquid, depending upon the extent to which it ismiscible with the oil undergoing treatment.

The individual layers afterseparation may be removed and the solventliquid recovered there-s from, or they may be subjected to furthertreatment with additional quantities of solvent liquid. By subjectingthe'separated fractions to repeated extraction, a series of fractions ofdiiferingcharacter may be. separated from the original oil.

This is of particular advantage in connection with the extracting ofmineral oil for the produc tion of lubricating oils of diiferinglubricating properties. Lubricating oil fractions are usually composedof various groups of hydrocarbons,

the degree of separation between the paraflinic 30 and naphthenicbodies. In this way, lubricating oil products of difieringcharacteristics, such as viscosity index, may be produced as desired.

By way of example, in practicing our invention, one part of untreatedlubricating oil distillate 35 derived from a mid-continent crude bydistillation under diminished pressure,v is mixed with about'two parts01' a; solvent liquid mixture composed of about equal parts of .furfuraland an 40 ester of the cyclic hydrocarbons such as phenyl acetate orfur'furyl acetate. This mixture is subiected to agitation and heating inorder to produce a homogeneous mixture or to effect complete solution01'- the oil in the solvent. 45

The mixture is then allowed to settle, forming an upper and a lowerlayer. The temperature at which this separation into two layers iseffected will depend upon the degree of separation desired and may,forexample, range from around 0 50 F. to 200 F. or higher.

In some instances, it may be desirable to heat the mixture to arelatively high temperature in order to obtain complete solution of theoil in the solvent, and then allow the mixture to 55 cool to a desiredtemperature where, upon settling, separation into two layers results.

The upper layer will comprise the undissolved hydrocarbons or thoseconstituents of the oil characterized by having a relatively highviscosity index, while the lower layer will be composed of soluble byhydrocarbons and constituents of low viscosity index dissolved in thebulk of the solvent liquid mixture. 7

The layers are then separately withdrawn and the solvent liquid removedfrom the oil by vacuum distillation or by other suitable means. Ifdesired, the separated layers may be subjected to treatment withadditional quantities of the solvent or additional quantities of asolvent liquid mixture composed of furfural and ester in proportionsdifiering from those' used in the initial extracting step. In this way,it is possible to obtain from the lubricating oil distillate a series offractions of diifering viscosity index, and other characteristics as maybe desired.

The lubricating oildistillate may be subjected to theforegoingextraction treatment either before or after dewaxing by any of the wellknown methods for the separation of wax from waxbearing mineral oil.

The invention is not restricted to mixing with the furfural an estersolvent having relatively less selective action but may embrace mixingtherewith a solvent having either greater or less selectivity, orpossessing a selective action upon certain constituents from which thefurfural may exert little or no solvent action. It has been found thatfurfural is more selective toward naphthenic hydrocarbons of highviscosity than toward naphthenic hydrocarbons of low viscosity, andtherefore, it is of advantage to use, in admixture with the furfural, asolvent liquid having somewhat the opposite range of selectivity.Accordingly, a combination of such solvents ofiers an advantage for themore complete removal of both light and heavy fractions of naphthenesfrom a wide range of naphthenic or parafiinic lubricating oil fractions.7

Furthermore, the invention is not necessarily limited to the treatmentof lubricating oil fractions but may be applied to the refining andpurification of various hydrocarbon or mineral oil fractions, includingnaphtha, kerosene, etc., as well as various residual or distillatefractions or products derived from petroleum or other sources. It isalso applicable to the treatment and purification of the crude petroleumitself.

Under ordinary conditions, the extraction treatment with a mixturecomprising furfural and an ester of the cyclic hydrocarbons 'may beapplied to a raw distillate or oil fraction to produce a finishedmerchantable product. However, in the case of oils of exceedingly highsulphur content or unusual characteristics, as regards sludge orcarbon-forming tendencies, it may be found desirable to supplement thetreatment by the usual acid, alkali and doctor treatment, applied eitherbefore or after the treatment with the solvent mixture.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims. 7

We claim:

1. The method of refining and purifying mineral oil to separatesulphur-bearing bodies, aromatic, unsaturated compounds and otherundesired bodies from the relatively more parafiinic portion of the oilwhich comprises extracting the oil with furfural in admixing withfurfuryl acetate whereby the oil is separated into a refined oilfraction. having desired characteristics and an extract fractioncontaining the undesired constituents.

2. The method of separating mineral lubricating oil containingconstituents of relatively low and relatively high viscosity index whichcomprises extracting the oilwith a solvent comprising furfuryl acetatewhereby the mixture separates into an extract phase containingrelatively low viscosity index constituents'and a raflinate phasecontaining relatively high viscosity index constituents, separating theresulting phases and removing solvent therefrom.

ROBERT E. MARLEY. HOWARD H. GROSS.

